Plants are under constant attack by pathogens. To protect themselves, plants produce an array of defense proteins. Kiwellins are a family of secreted plant proteins that are common in many plant species. However, their biological functions remain largely unknown. An exception is Kwl1 from kiwi fruit, which acts as a human allergen. Scientists at the Max Planck Institute for Terrestrial Microbiology and collaborators at the LOEWE Center for Synthetic Microbiology (Synmikro) in Marburg and the Faculty of Biology of the Philipps-Universität Marburg have described a biological function to a plant kiwellin for the first time. They detected a maize kiwellin that specifically inhibits the chorismate mutase activity of the U. maydis effector Cmu1. This finding highlights that kiwellins contribute to plant defense against a fungal pathogen.